Select Page

How your metabolism responds over a year after an ill-advised diet


I wrote Metabolic Damage and the Dangers of Dieting in 2007. At that time, whenever anyone was writing on the topic it was framed as a debate over whether or not “metabolic damage” was even real. On the one side, people argued that metabolic damage was real; on the other, people would argue that this was simply “psychological weakness.”

But those days are long past, and that debate is over: metabolic damage as a result of dieting continues to show up in solid research and academia.

It is now well-known what the calorie-deprivation approach can do in terms of harming your metabolism and other hormonal and biological systems. I should point out that outside the fitness and diet industry, the term “metabolic damage” is known by other names as well. I have a feeling that in the coming years you will be hearing the terms “metabolic dysregulation” and “metabolic compensation system” a lot more, as the real science starts to finally seep into the public’s awareness.

So let’s just stop here and consider that any diet – in order to be healthy and sustainable – cannot just be about weight loss! A healthy and sustainable diet-strategy must also be about maintaining and even optimizing metabolic function and capacity. Otherwise the long-term consequences can be devastating.

For people who are 40 and over, and for peri-menopausal women, you face a double-edged sword when it comes to weight-control. It is very likely that will you gain some unwanted weight during these years – but it is even more likely that severe calorie-deprivation dieting as an “answer” to such weight-gain will cause more harm than good.

As we age, our hormones change. This is true of everyone. If you add dieting into the mix, you can turn what is natural (though admittedly undesired) weight gain into an out-of-control spiral. Calories-counting and calorie-deprivation are not the way out of weight-gain for you as you get older.

Consider this startling long-term study by Sumithran et al. published in The New England Journal of Medicine (references included at the end)

Fifty men and post-menopausal women forced themselves to eat less for 10 weeks. (If you can’t tell, the keyword here is “forced.”) To no one’s surprise, they all lost weight… initially. What the study revealed is that forcing weight off creates dysfunction and obstruction in the hormonal and metabolic feedback loops that operate to control weight and to function in a healthy manner (e.g. peptide YY, cholecystokinin, gastric polypeptides, ghrelin, and leptin, just to name a few). This is what happens when you to try to override your biological hardwiring.

So what were the consequences to this disruption and obstruction, long after the 10 weeks of dieting were over? They were something the likes of which many of you likely know all-too-well from your own previous dieting experiences.

As a physiological response to the lack of energy coming in, the subjects’ appetites and cravings increased. To go along with this, the number of calories they burned also decreased at the same time. As you can imagine, this is a terrible combination for long-term weight-control. Their internal biochemical and hormonal and metabolic systems were adjusting for the lack of energy coming in.

No one fools the body for long, and no one forces the body into change without it going into survival mode. The subjects’ bodies were fighting back to return them to their previous bodyweight set point. The body does not know the difference between a calorie-deprivation “diet” and real starvation. The body will respond to both scenarios the same way—by protecting itself for survival. Anyone familiar with my writings about the consequences of dieting knows that the result seen in this study is not a novel or unusual outcome.

For the past few decades, there has actually been a fair bit of research about the biological, metabolic and hormonal adaptations to forced dieting (consider Ansel Keys’ work in the 50s). But this study kept going where other studies usually stopped; this one really showed the long-term effects. These researchers showed that even one whole year after following a mere 10 weeks of forced calories-deprivation, the alterations in appetite, cravings, and slower calories-burn continued to persist, even a year after the dieting had stopped and the weight was regained!

What this research study showed is the body’s instinctual desire to “fight back.” And the body fights back  long-term, as a sort of “biological insurance policy” if you will. As for the older participants in this study, well, their biological, metabolic and hormonal systems were synergistically engaged for the longterm in multiple compensatory mechanisms, all to get the body to do everything it could do to restore itself to its previous set-point. Part of this includes implementing biological, hormonal, and metabolic safeguards to prevent that kind of weight-loss from happening again: your body makes you hungry, and crave more food, because it wants you to store more if it just in case.

The researchers noted that the “changes in appetite persist[ed] for 12 months,” and there was a “greater-than-predicted decline in 24-hour energy expenditure” (p. 1603). Even a year later, the subjects’ bodies were still “vigorously resisting” this misguided attempt at weight-loss-thru-calories-deprivation, and their systems were “desperately trying to regain weight.”

This is just one example of many.

If you really want long-term weight-loss and sustainable weight-control, you have to rethink the whole notion of the term “diet.” I prefer the term “diet-strategy,” and it must always entail long-term considerations and the metabolic compensatory system as well. This is “the biology of weight-control” and it must be considered and understood if your goal is substantial and sustainable weight-loss.

The key is to coax your bodyweight set-point down in a way where your body is not threatened. You have to learn to work with human biology, and not think you can force it to do anything other than what it has evolved to do.

What most people require now for long-term sustainable weight-loss and weight-control is not a laser-like focus on “weight-loss”; rather, what’s need is a focus on metabolic healing and recovery!

This becomes especially true if you are over 40 and have weight to lose and/or if you are a peri-menopausal woman seeking to optimize metabolic and hormonal function in a way that supports fat loss while preserving lean mass.

You can’t do that through the usual diet-mantra of “calories-counting, calories-equation faulty math.” It’s just not how your body works. Your body is even more susceptible to “metabolic dysregulation” as you age and try to diet off weight. Now more than ever it is important that you work with your body, not against it.


Keys, A., Brozek, J., Henschel, A., Mickleson, O., and Taylor, H.L. The Biology of Human Starvation (2 vols) (1950) Minnesota: University of Minnesota Press

Keesey, Richard E, and Matt D Hirvoven. “Body Weight Set-Points: Determination and Adjustment.” The Journal of Nutrition 127.9 (1997): 1875S–1883S. Print.

Sumithran, Priya et al. “Long-Term Persistence of Hormonal Adaptations to Weight Loss.” The New England Journal of Medicine 365.17 (2011): 1597–1604.